Although there has been significant awareness to use “environmentally friendly” chemicals and processes, most of the photopolymers that are currently used in such technologies as semiconductor device fabrication, flat-panel device or antireflective coatings involve organic solvents and developed in solvents or aqueous solutions containing organic bases. Thus there is a growing need for aqueous based development technologies and water soluble materials that are “environmentally friendly.”
One such example of a class of water soluble polymer is glycopolymer, which is also often referred to as “sugar polymer.” Glycopolymers have been found useful for a variety of biotechnical applications. While initially, such glycopolymers were prepared by radical polymerization of olefin or acrylamide monomers having sugar residues as pendent groups, in 1995 Fraser et al. (“Synthesis of Glycopolymers of Controlled Molecular Weight . . .”, Macromolecules, 1995, v. 28, p. 7248-7255) was among the first to report the Ring-Opening Metathesis Polymerization (ROMP) of glucose substituted norbornene monomers. Fraser et al. reported using Ruthenium carbene catalysts to initiate the polymerization. Following Fraser et al., Nomura et al., reported the use of Molybdenum catalyzed living ROMP techniques (“Preparation of “Sugar-Coated” Homopolymers and Multiblock ROMP Copolymers”, 1996, v. 29, p. 540-545). While such norbornene-type ROMP polymers may be useful for biological and/or biotechnical applications, the presence of unsaturation in the polymer backbone is known to limit their applications in other applications, such as optoelectronic applications, among others. For instance, their lack of thermo-oxidative stability and resistance to reactive ion etching, makes them unsuitable for use in microelectronic and optoelectronic devices and fabrication thereof. Even more importantly due to the presence of unsaturated double bonds, ROMP polymers also exhibit high absorbance at low wavelengths thus rendering them unsuitable for optoelectronic applications.
In 1999, Havard et al. reported the development of sugar-containing polymethacrylates that were useful as photoresists (“Photoresists with Reduced Environmental Impact: Water-Soluble Resists Based on Photo-Cross-Linking of a Sugar-Containing Polymethacrylate”, Macromolecules, 1999, v. 32, p. 86-94). While Puech et al. and Hu, et al (New J. Chem. 1997, 21, 1229 and Tet. Lett. 2002, 43, 1775, respectively), have had some success at forming norbornene-type vinyl addition polymers, such methods appear limited, in that the polymers obtained had low weight average molecular weights (Mw), (18,000 or less), or to a process having very high catalyst loading ratios (e.g. from 10:1 to 100:1).
Therefore it would be advantageous to provide water soluble norbornene-type vinyl addition polymers having at least one of (a) high molecular weights (including a process for making such polymers); (b) controllable molecular weights; and (c) a polymerization process for such polymers that does not require the high catalyst loading of the prior art.